CHAPTER 1

PLANNING A NETWORK TOPOLOGY

WINDOWS SERVER 2003 & NETWORK INFRASTRUCTURE

Network infrastructure – a set of physical & logical components that provides connectivity, security, routing, management, access & other important features on a network.

Network planning phase is the duration when engineers selects hardware & software components that will compose the network infrastructure & specify particular location, installation & configuration of those components.

Implementing a network infrastructure – the process of evaluating, purchasing & assembling the specified components, & installing them according to the design plan.

PHYSICAL INFRASTRUCTURE

A networks physical infrastructure is its topology! Physical infrastructure – the physical design of

the network along with hardware components such as cabling, routers, switches, hubs, servers & workstation.

Ex; Physical infrastructure for small network is simple & consists of computers, hub & few cables.

Ex; Physical infrastructure for Medium-to-large networks can be very much complex consists of massive amount of computers, a vast of cables, multiple interconnected hubs/ switches, wireless connectivity, remote client access etc.

LOGICAL INFRASTRUCTURE

Involves the many software elements that connects, manage & secure host on the network.

Allows communication between computers over the path described in the physical topology.

Consists of both abstract software elements, such as networking protocols & concrete elements such as specific software products.

Ex; medium-to-large network – one probably decides to use TCP/IP protocols for network & transport layer communications.

PLANNING A NETWORK INFRASTRUCTURE

Is the most complicated part as during this phase you create the ‘blueprint’ of the network & maintain it later.

Question to be asked when planning is: what tasks do the network users have to complete? Answering it requires the designer to redefine the

types of communication needed & the software they need to accomplish their task.

Ex; network that allows users to access streaming video (elements to be considered is the bandwidth, internet speed etc)

PLANNING A NETWORK INFRASTRUCTURE Factors involved in choosing network

infrastructure; Network size Tasks the network users have to accomplish Security

Security infrastructure As all the possible dangers to a network is

identified, the designer have to plan suitable security infrastructure to protect the network.

Might include advance configuration of the operating systems, services & applications as well as additional components such as digital certificates.

IMPLEMENTING A NETWORK INFRASTRUCTURE

It is important to understand the organizational aspects of the product deployment, such as the allocation of IP addresses & designing a DNS namespace.

Involves on the selection of protocols, operating system, applications, & security mechanism that satisfies the requirement of network users as per the planning process.

Tasks are delegated to the experts (mostly external contractors) to make sure it is properly carried out. Ex; laying of cables.

MAINTAINING A NETWORK INFRASTRUCTURE

Includes tasks such as performing software updates, monitoring network performance and processes & trouble-shooting problems.

For large network infrastructure, each release must be carefully tested on a lab network before deploying it on the production network.

Lab network – a protected environment that duplicates the real network.

Network administrator is responsible in maintaining the network infrastructure.

Network failure will result in reduced productivity & loss in revenue.

SELECTING DATA LINK LAYER PROTOCOLS

Protocols – are the languages computers use to communicate between each other on a network.

OPEN SYSTEMS INTERCONNECTION (OSI)

The seven layers of the OSI model define functions that are implemented in various networking protocols such as Ethernet & TCP/IP.

A computer on a network does not necessarily runs 7 different protocols with one layer corresponding with another.

OPEN SYSTEMS INTERCONNECTION (OSI)

Physical Defines the nature of the network medium, the

actual fabric of the network that joins all computers together & the nature of the signals transmitted over the medium. (Ex; copper cables, fiber optics, wireless media etc)

Data-Link Defines the interface between the network

medium & the software running on the computer. Responsible for a local traffic on a single network

Functions : packet addressing, media access control & formatting the frame used.

Consists of logical link control (LLC) sub-layer & media access control (MAC) sub-layer.

OPEN SYSTEMS INTERCONNECTION (OSI)

Network Defines the functions that provide end-to-end

communications between computers on different networks. Responsible for directing traffic to its destination.

Functions; routing, packet sequencing, congestion control, addressing etc.

Transport Provides functions that complements those of

network layer including guaranteed delivery, flow control & end user error detection.

OPEN SYSTEMS INTERCONNECTION (OSI)

Session Provides many functions involved in the

regulation of the dialogue between 2 computers communicating over the network.

Presentation Also known as ‘syntax layer’ is responsible for

translating each computers native syntax into a common transfer syntax readable by other computers on the network. (also provide data compression & encryption)

Application Provides the interface between the networking

protocol stack & the software running on the computer. Ex: interface for email, file transfer, telnet etc

SELECTING A DATA LINK LAYER PROTOCOL

Primarily a matter of choosing an appropriate network medium.

Most common data link layer protocol is Ethernet & Token ring.

Criteria involved in selecting the data link; Distance between workstations (media type) Transmission speed required Nature of the traffic the network will carry & its

amount Cost

SELECTING A MEDIA TYPE

Network media consists of cables – bounded media Network media without cables(wireless) –

unbounded media

Unshielded Twisted Pair (UTP) Type of copper cable that consists of 4 pairs of

wires, each of which is twisted together & contained inside a protective shield. (ex; CAT5)

CAT 5

RJ 45

RJ 45 Jack

You may install UTP cables using Star topology, in which you connect each workstation in the network to a central hub. UTP cables are cheap & easier to install but it can only

support distances up to 100meters ! Not secure as unauthorized user can still tap into the

cables. Since the signals are electric waves, so they can get

affected by electromagnetic interference. Usually supports speed up to 10Mbps

SELECTING A MEDIA TYPE

Fiber optic Consist of a strand of plastic or glass that carries

signals in the form of light pulses. Advantages;

Immune to electromagnetic interference as it uses light signals.

Less susceptible to attenuation (weakening of signal due to distance).

Covers longer distances : Multi-mode fiber optics = 400-2000 m, single-mode fiber optics = 100 km

Secure as unauthorized user cannot easily tap into the cable & intercepts its signals.

Disadvantages; Costly Need special skills to install & maintain it. Cables can not be bend to sharply.

SELECTING A MEDIA TYPE

Wireless networking A network without the use of cables & uses radio

waves. Can be either adhoc topology (2 or more

computers with wireless network adapters) or infrastructure topology(enables wireless computers to interact with a standard cable network using access point). Advantages ; less expensive, available in the market,

supports up to 11 Mbps, situations where cables are impractical (lobby, plaza).

Disadvantages ; subject to interference of environmental factors such as number of walls, climate, other electrical equipment. Effective transmission range can vary from minute to minute, location-to location.

SELECTING TRANSMISSION SPEED Is a matter of determining your users current & future

requirements & balancing them against the budget.

Using Token Ring Doesn’t support as many media types as Ethernet,

and quite slow. Uses Media Access Control (MAC) which allows one

computer at a time to take possession of the network, so that they can transmit data without any collision.

Ethernet 10Mbps

Fast Ethernet 100Mbps

Gigabit Ethernet 1000Mbps / 1Gbps

SELECTING NETWORK / TRANSPORT LAYER PROTOCOLS Windows Server 2003 includes support for;

TCP/IP Internet Packet Exchange (IPX) NetBIOS Extended User Interface (NetBEUI)

TCP/IP Is the industry standard protocol suite at the

network & transport layers. Due to its self-contained addressing system,

TCP/IP can support any type of computer network & can expand to any size.

2 primary protocols in the TCP/IP suite are; Internet Protocol (IP) – network layer Transmission Control Protocol (TCP) or User Datagram

Protocol (UDP) – transport layer

IP datagram consists of sender & receiver’s address. – envelope!

Whether a network communication process uses IP with TCP or IP with UDP, depends on the requirement of the application generating the network traffic.

TCP – connection oriented. Acknowledgement is a must as it involves large amount of data that must arrive intact at destination.

UDP – connectionless. No acknowledgement, no connection has to be established first. Usually for brief exchange of data such as request & response messages. Loss of packet is possible.

SELECTING NETWORK / TRANSPORT LAYER PROTOCOLS

SELECTING NETWORK / TRANSPORT LAYER PROTOCOLSIPX Designed for use with the Novell Netware operating

system (privately owned), but windows can also use it for its own file sharing – NWLink

Does not have a self-contained addressing system instead uses the hardware address coded into each network interface adapter to identify the system

NetBEUI A simple protocol that supports window file sharing on

small networks, but not routable hence unsuitable for internetwork installations.

Uses the NetBIOS name specified by the installer during the window setup procedure as the computer’s identifier on the network.

LOCATING NETWORK RESOURCES Creating network blueprint that determines the

locations of workstations, cables, peripherals, connectivity devices & servers. Criteria to consider when planning the location; Access by users to the equipment they need to perform

their task Physical security of the devices Business requirements such as cost, appearance,

portability & expandability.

Locating Workstations Determining the type of computer & exact

placement of the equipment in relation to the desk is a must. Ex; tower CPU, horizontal small form, laptops, cables etc

LOCATING NETWORK RESOURCES

Locating Peripherals Location for printer placement & other shared

peripherals is important & ergonomic issue is given priority.

Physical security of the peripherals such as expensive color cartridges etc

Locating Cables Cable diagram is very important as it is likely to be

invisible once the construction of the network is completed. Technicians must know where the cables are located for trouble-shooting & maintenance.

Planning cable layout requires understanding the limitations imposed by the protocols selected & familiarity with the network site. Issues to be considered : internal / external cabling, the

distance of fixtures, electromagnetic interference

LOCATING NETWORK RESOURCES

Locating Connectivity Devices Determine where hubs & patch panels will be

located to allow cables to be connected. Limiting factor is the maximum allowable length

of the network cables. Ex: UTP cable run can be up to 100m, so the

connectivity devices location have to be less than 100m from the nearest workstation.

Horizontal networks – individual LANs on each floor

Backbone network – LAN running between the floors & connecting horizontal networks.

LOCATING NETWORK RESOURCES

Locating Servers Servers are the most important components

of business network hence should be more physically secured as well as protected against power interruptions.

Server locations depends on who must access the server, where the serves traffic originated & who will be responsible for maintaining the server.

Can be either placed on individual department or in single data center.